Liquid crystal display device

ABSTRACT

A liquid crystal display (LCD) device in which a movement of a light guide plate received in a mold frame can be minimized. A light guide plate has catching jaws and projections. The catching jaws are formed by cutting at least one corner of an end portion of the light guide plate receiving the light from the lamp unit. The projections extend outwardly from sidewalls of the catching jaws, which respectively have a thinner thickness than the catching jaws. A mold frame receives the light guide plate and the lamp unit and has catching bosses and recesses. The catching bosses are formed at positions corresponding to the catching jaws on a bottom surface of the mold frame to engage the catching jaws to fix the light guide plate in the mold frame. The recesses are formed at positions corresponding to the projections at sidewalls of the mold frame to receive the projections.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/196,986, filed Jul. 18, 2002 now U.S. Pat. No. 7,092,048, bySeung-Chul Jeong, entitled “LIQUID CRYSTAL DISPLAY DEVICE;” which claimspriority of Korean Patent Application No. 2001-43706 filed Jul. 20,2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display (LCD) device,and more particularly to a LCD module and a LCD device that can minimizethe movement of a light guide plate received in a mold frame byimproving the structure of the light guide plate and the mold frame ofthe LCD device.

2. Description of the Related Art

Recently, an information processing device has been developed to havevarious shapes, various functions, and a rapid information processingspeed. The information processed in the information processing devicehas an electrical signal. In order to confirm the information processedin the information processing device with the naked eye, a displaydevice that functions as an interface device is needed.

Recently, a LCD device that is lighter, and smaller than a CRT typedisplay device has been developed. The LCD device now displays a fullcolor spectrum in a high resolution. As a result, the LCD device iswidely used as a computer monitor, a television receiver, and otherdisplay devices.

The LCD device applies a voltage to a liquid crystal layer to change themolecular arrangement of the liquid crystal layer. The LCD devicechanges the optical properties in the liquid crystal and uses themodulation of a light by using a liquid crystal cell.

There are two kinds of LCD devices: a TN (Twisted Nematic) type, and anSTN (Super-Twisted Nematic) type. Also, they can be grouped into anactive matrix display type that uses a switching device and a TN liquidcrystal, and a passive matrix display type that uses a STN liquidcrystal according to the driving type.

The active matrix display method is used in a TFT-LCD and drives an LCDby using a thin film transistor (TFT) as a switch. The passive matrixdisplay method does not use any transistor and does not require acomplex circuit.

Further, LCD devices are grouped into a transmissive LCD device thatuses a backlight and a reflective LCD device that uses an exterior lightsource, according to a method for using a light source.

The transmissive LCD device using the back light as a light source isrelatively heavy and voluminous due to the back light, but it is widelyused since it does not use an exterior light source and displays animage independently from the exterior light source.

FIG. 1 is an exploded perspective view schematically showing aconventional LCD device. FIG. 2 is a partial exploded perspective viewof the LCD device shown in FIG. 1.

Referring to FIG. 1, the LCD device 900 has a LCD module 700 to which animage signal is applied to display an image, and a front case 810 and arear case 820 for receiving the LCD module 700.

The LCD module 700 has a display unit 710, which includes a LCD panelfor displaying the image.

The display unit 710 has a LCD panel 712, an integrated and printedcircuit board 714, a data side tape carrier package 716, and a gate sideflexible circuit board 718 manufactured by the COF (chip-on-film)method.

The LCD panel 712 has a TFT substrate 712 a, a color filter substrate712 b, and a liquid crystal layer (not shown) interposed therebetween.

The TFT substrate 712 a is a transparent glass substrate on which TFTsare formed in a matrix shape. Data lines are connected to sourceterminals of the TFTs, and gate lines are connected to gate terminals ofthe TFTs. Pixel electrodes of indium tin oxide (ITO), which is atransparent conductive material, are formed on drain terminals.

If electrical signals are inputted to the data lines and to the gatelines, the electrical signals are inputted to the source terminals andto the gate terminals of TFTs and the TFTs are turned on or off so thatelectrical signals for forming pixels are outputted to the drainterminals.

The color filter substrate 712 b is attached to the TFT substrate 712 a.RGB pixels that pass light through to realize color display are formedon the color filter substrate 712 b by a thin film process. A commonelectrode comprised of ITO is coated on the front surface of the colorfilter board 712 b.

If electric power is applied to the gate terminals and to the sourceterminals of the transistors and the TFTs are turned on, an electricfield is formed between the pixel electrode on the TFT substrate and thecommon electrode of the color filter substrate. The arrangement anglesof the liquid crystals injected between the TFT substrate 712 a and thecolor filter substrate 714 b are changed by the electric field, and thelight passages are changed due to the arrangement angle changes toobtain a desired pixel status.

A driving signal and a timing signal are applied to the gate line and tothe data line of the TFT to control the arrangement of the liquidcrystal of the LCD panel 712 and the timing when the liquid crystal isarranged. The data side tape carrier package 716, which is a kind offlexible circuit board for determining the timing when the data drivingsignal is applied, is attached to the source side of the LCD panel 712,and the gate side flexible circuit board 718 manufactured by the COFmethod for determining the time when the gate driving signal is appliedis attached to the gate side of the LCD panel 712.

The integrated and printed circuit board 714 for receiving image signalsfrom outside of the LCD panel 712, and for applying driving signal tothe gate line and to the data line, is connected to the data tapecarrier package 716 of the data line side of the LCD panel 712. Theintegrated printed circuit board 714 has a source portion to which theimage signals generated from an exterior information processing device(not shown), such as a computer, are applied to provide the data drivingsignals to the LCD panel 712 and a gate portion for providing the gatedriving signals to the gate line of the LCD panel 712. Namely, theintegrated printed circuit board 714 generates the gate driving signalsfor driving the LCD device, the data signals, and a plurality of timingsignals for applying the signals. The gate signals are applied to thegate line of the LCD panel 712 through the gate side flexible circuitboard 718, and the data signals are applied to the data line of the LCDpanel 712 through the data tape carrier package 716.

A back light assembly 720 for providing a uniform light to the displayunit 710 is provided under the display unit 710. The back light assembly720 has a lamp 721, which is provided on one side of the LCD module 700to generate the light. The lamp 721 is protected by a lamp cover 722. Alight guide plate 724 has a size corresponding to the LCD panel 712 ofthe display unit 710, and is located under the LCD panel 712. The lampside of the light guide plate 724 is thicker than the other sideopposite to the lamp side, and it guides the light generated by the lamp721 towards the display unit 710 to change the passage of the light.

A plurality of optical sheets 726, for making the luminance of the lightirradiated from the light guide plate 724 and passed towards the LCDpanel 712 uniform, are provided above the light guide plate 724. Areflection plate 728, for reflecting the light leaked from the lightguide plate 724 to increase the efficiency, is provided under the lightguide plate 724.

The display unit 710 and the back light assembly 720 are fixed andsupported by a mold frame 730 that is a receiving receptacle. The moldframe 730 has a box-shape, and the upper surface of the mold frame 730is open. That is, the mold frame 730 has four side walls and a bottomsurface, and openings, for bending the integrated printed circuit board714 along the outer side surface of the mold frame 730 and positioningthe integrated printed circuit board 714, are formed on the lowersurface of the bottom.

A chassis 740 for bending the integrated printed circuit board 714 ofthe display unit 710 and the gate tape carrier package 718 outside ofthe mold frame 730, and for fixing the integrated printed circuit board714 of the display unit 710 and the gate tape carrier package 718 to thebottom surface of the mold frame 730 to prevent the deviation of thedisplay unit 710, is provided. The chassis 740 has a box-shape in thesame manner as a mold frame 730. The upper surface of the chassis 740 isopened to expose the LCD panel 710, and the side walls are bent inwardlyto cover the upper surface peripheral portion of the LCD panel 710.

On the other hand, referring to FIG. 2, first and second catching bosses731 and 732 are integrally formed with the mold frame 730 on the cornerportions of the mold frame. on which the lamp 721 (see FIG. 1) isinstalled in the receiving space of the mold frame 730. The corner of anend portion, which is located on the side of the lamp 721 in the lightguide plate 724 received in the mold frame 730, is cut off to form firstand second catching jaws 724 a and 724 b.

FIG. 3 shows the state in which the light guide plate shown in FIG. 2 isreceived in the mold frame. FIG. 4 is a partially enlarged view ofsection “P1” showing the fixing structure of the light guide plate shownin FIG. 3 and the mold frame. FIG. 5 is a top view showing the size ofthe light guide plate shown in FIG. 3.

Referring first to FIG. 3, if the light guide plate 724 is received inthe mold frame 730, the first and second catching jaws 724 a and 724 bare engaged with the first and second catching bosses 731 and 732.Therefore, even when exterior impacts are applied to the LCD device 900,the light guide plate 724 does not move towards the lamp 721 due to thepresence of first and second catching bosses 731 and 732.

However, it is now desirable for the thickness of the side wall of themold frame 730 to become thinner so as to minimize the size of the LCDdevice 900. Further, as shown in FIG. 5, the width of the light guideplate 724 of the end portion of the side of the lamp 721 is identical tothe width of the end portion of the opposite end portion. That is, widthW1 equals width W2. Therefore, it is not easy to sufficiently guaranteethe thickness of the first and second catching bosses 731 and 732 thatare integrally formed with the mold frame 730. Therefore, as shown inFIG. 4, the catching force of the first and second catching jaws 724 aand 724 b of the light guide plate 724 and the first and second catchingbosses 731 and 732 of the mold frame 730 can not be sufficientlyguaranteed so that preventing the light guide plate 724 from movingtowards the lamp 721 is difficult.

On the other hand, if the width of the light guide plate 724 increasesby the gap between the light guide plate 724 and the mold frame 730 toguarantee the catching force (i.e., by width W3), the catching force ofthe first and second catching jaws 724 a and 724 b and the first andsecond catching bosses 731 and 732 can be obtained. However, without thegap between the light guide plate 724 and the mold frame 730, thethermal expansion space of the light guide plate 724 according to thetemperature change and the humidity change cannot be guaranteed, therebygreatly inducing the folding phenomenon. Especially, in the wedge typelight guide plate 724 shown in FIGS. 1 and 2, since the thermalexpansion rate is large at the portion where the light guide plate 724is thin, the sufficient gap between the light guide plate 724 and themold frame 730 is necessary.

On the other hand, even though it is not shown in the figure, themovement of the light guide plate 724 can be prevented by protruding aportion of both side surfaces of the light guide plate 724, forming aboss, and forming a recess at a position that corresponds to the boss onboth side walls of the mold frame 730. However, in that case, it is noteasy to guarantee the catching force between the boss and the recess andto prevent the light inputted from the lamp 721 from being concentratedat a corner portion defined by the boss and the recess.

SUMMARY OF THE INVENTION

The present invention has been made to solve the above-mentionedproblems, and accordingly it is an object of the present invention toprovide a LCD module that can minimize the moving of a light guidedevice received in the mold frame.

It is another object of the present invention to provide a LCD devicethat can prevent a light guide device received in the mold frame frombeing damaged.

To achieve the object of the present invention, a LCD module accordingto the present invention includes a light guide plate for guiding lightemitted from a lamp unit to a display unit to display images. The lightguide plate has a catching jaw formed by cutting at least one corner ofa first end portion receiving the light from the lamp unit and aprojection extending outwardly from sidewalls of the catching jaws andhaving a thinner thickness than that of the catching jaws. A mold framereceives the light guide plate and the lamp unit. The mold frame has acatching boss and recess. The catching boss is formed at a firstposition corresponding to the catching jaw on a bottom surface of themold frame to engage with the catching jaws so as to fix the light guideplate in the mold frame. The recess is formed at a second positioncorresponding to the projection in a sidewall of the mold frame toreceive the projection.

To achieve the other object of the present invention, a LCD deviceaccording to the present invention includes a backlight assemblyincluding a light guide plate for guiding light emitted from a lamp unitto a display unit to display images. The light guide plate has acatching jaw and a projection. The catching jaw is formed by cutting atleast one corner of a first end portion receiving the light from thelamp unit. The projection extends outwardly from a sidewall of thecatching jaws and has a thinner thickness than that of the catching jaw.A mold frame receives the light guide plate and the lamp unit. The moldframe has a catching boss and recess, the catching boss being formed ata first position corresponding to the catching jaw on a bottom surfaceof the mold frame to engage with the catching jaw so as to fix the lightguide plate in the mold frame. The recess is formed at a second positioncorresponding to the projection in a sidewall of the mold frame toreceive the projection. A top chassis is oppositely combined to the moldframe, for guiding the display unit while fixing the display unit andthe backlight assembly to the mold frame.

The projections have a width that gradually decreases from one end toanother end of the light guide plate. The light guide plate is a wedgetype of light guide plate of which a thickness is gradually thinner fromone end to another end thereof. The respective recess formed in arespective sidewall of the mold frame has a width that is larger thanthe thickness of the respective projection but is smaller than thethickness of the respective catching jaw. A thickness of an area inwhich the catching jaws are engaged with the catching bosses is the sameas the projections.

In the LCD module and the LCD device, even if exterior impacts areapplied to the liquid crystal device, since the catching bosses of themold frame are respectively and rigidly engaged with the catching jaws,the light guide plate is prevented from moving towards the lamp.

In addition, even though the exterior impacts are applied to the sidewalls of the mold frame, the projections and the catching jaws can beprevented from being damaged because the projections are respectivelyreceived in the recesses of the mold frame. Further, since theprojections are formed so as to have a slope shape, the concentration ofthe light inputted from the lamp is prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the present invention willbecome readily apparent by reference to the following detaileddescription when considered in conjunction with the accompanyingdrawings wherein:

FIG. 1 is an exploded perspective view for schematically showing aconventional LCD device;

FIG. 2 is an exploded perspective view for showing the structure of alight guide plate and a mold frame shown in FIG. 1;

FIG. 3 is a view for showing the state in which the light guide plateshown in FIG. 2 is received in the mold frame;

FIG. 4 is a partially enlarged view for showing the horizontal fixingstructure of the light guide plate and the mold frame shown in FIG. 3;

FIG. 5 is a top view for showing the size of the light guide plate shownin FIG. 3; FIG. 6 is an exploded perspective view for showing a LCDdevice according to a first preferred embodiment of the presentinvention;

FIG. 7 is an exploded perspective view for showing the structure of alight guide plate and a mold frame of the LCD device according to thefirst preferred embodiment of the present invention that are shown inFIG. 6;

FIGS. 8 and 9 are partially cut perspective views for showing thestructure of the light guide plate shown in FIG. 7;

FIG. 10 is a view for showing the light guide plate according to thefirst embodiment of the present invention shown in FIG. 7, in which thelight guide plate is received in the mold frame;

FIG. 11 is a partially enlarged view for showing the horizontal fixingstructure of the mold frame and the light guide plate shown in FIG. 10;

FIG. 12 is a top view for particularly showing the structure of thelight guide plate shown in FIG. 10;

FIGS. 13 and 14 are views for showing the state in which a catching bodyof the light guide plate is combined within a recess of the mold frameshown in FIG. 11;

FIGS. 15 and 16 are views for showing the other state in which acatching body of the light guide plate is combined within a recess ofthe mold frame shown in FIG. 11; FIG. 17 is an exploded perspective viewfor showing a LCD device according to the second preferred embodiment ofthe present invention;

FIG. 18 is a view for showing the state in which a light guide plateshown in FIG. 17 is received in a mold frame;

FIG. 19 is a top view for particularly showing the structure of thelight guide plate shown in FIG. 11;

FIG. 20 is a sectional view for showing the sectional structure of thelight guide plate shown in FIG. 19; and

FIG. 21 is a top view for more particularly showing the combination ofthe light guide plate and the mold frame shown in FIG. 18.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinafter, a LCD module and a LCD device according to the preferredembodiments of the present invention will be described in detail withreference to FIGS. 6 to 21, which are attached hereto.

Embodiment 1

FIG. 6 is an exploded perspective view for schematically showing a LCDdevice according to a first embodiment of the present invention.

Referring to FIG. 6, the LCD device 100 has a LCD module 200 to which animage signal is applied to display images and a case 300, which includesa front case 310 and a rear case 320 for receiving the LCD module 200.The LCD module 200 has a display unit 210 including a LCD panel thatdisplays the images. A chassis 330 bends the integrated printed circuitboard 214 of the display unit 210.

The display unit 210 has a LCD panel 210, an integrated printed circuitboard 214, a data side tape carrier package 216 and a gate side flexiblecircuit board 218 manufactured by the COF method.

The LCD panel 212 has a TFT substrate 212 a, a color filter substrate212 b and a liquid crystal (not shown) interposed therebetween.

The TFT substrate 212 a is a transparent glass substrate on which TFTsare formed in a matrix shape. Data lines are connected to sourceterminals of the TFTs, and gate lines are connected to gate terminals ofthe TFTs. Pixel electrodes of indium tin oxide (ITO), which is atransparent conductive material, are formed on drain terminals.

If electrical signals are inputted to the data lines and to the gatelines, the electrical signals are inputted to the source terminals andto the gate terminals of the TFTs and the TFTs are turned on or off asthe electrical signals for forming pixels are outputted to the drainterminals.

The color filter substrate 212 b is attached to the TFT substrate 212 a.RGB pixels that pass light through to realize color display is formed onthe color filter substrate 212 b. A common electrode comprised of ITO iscoated on the front surface of the color filter board 212 b.

If power sources are applied to the gate terminals and to the sourceterminals of the transistors and the TFTs are turned on, an electricfield is formed between the pixel electrode on the TFT substrate 212 aand the common electrode on the color filter substrate 212 b. Thearrangement angles of the liquid crystals between the TFT substrate 212a and the color filter substrate 212 b are changed by the electricfield, and the light passage are changed due to the arrangement anglechanges to obtain a desired pixel status.

A driving signal and a timing signal are applied to the gate line and tothe data line of the TFT to control the arrangement of the liquidcrystal of the LCD panel 212 and the timing when the liquid crystal isarranged.

The data side tape carrier package 216, which is a kind of flexiblecircuit board determining the timing when the data driving signal isapplied, is attached to the source side of the LCD panel 212, and thegate side flexible circuit board 218 manufactured by the COF method fordetermining the time when the gate driving signal is applied is attachedto the gate side of the LCD panel 212.

The integrated printed circuit board 214 for receiving image signalsfrom outside of the LCD panel 212, and for applying driving signal tothe gate line and to the data line, is connected to the tape carrierpackage 214 of the data line side of the LCD panel 212. The integratedprinted circuit board 214 has a source portion to which the imagesignals generated in an exterior information processing device (notshown), such as a computer, are applied to provided the data drivingsignals to the LCD panel 212 and a gate portion for providing the gatedriving signals to the gate line of the LCD panel 212.

Namely, the integrated printed circuit board 214 generates the gatedriving signals for driving the LCD device, the data signals, and aplurality of timing signals for applying the signals. The gate drivingsignals are applied to the gate line of the LCD panel 212 through thegate side flexible circuit board 218, and the data signals are appliedto the data line of the LCD panel 212 through the data tape carrierpackage 216.

A back light assembly 220 for providing a uniform light to the displayunit 210 is provided under the display unit 210. The back light assembly220 has a lamp 221, which is provided on one side of the LCD module 200to generate the light. The lamp 221 is protected by a lamp cover 222. Alight guide plate 224 has a size corresponding to the LCD panel 212 ofthe display unit 210, and is located under the LCD panel 212. The lampside of the light guide plate 224 is thicker than the other sideopposite to the lamp side, and it guides the light generated in the lamp221 towards the display unit 210 to change the path of the light.

A plurality of optical sheets 226, for making the luminance of the lightirradiated from the light guide plate 224 and passed towards the LCDpanel 212 uniform, are provided above the light guide plate 224. Areflection plate 228, for reflecting the light leaked from the lightguide plate 224 to increase the light efficiency, is provided under thelight guide plate 224. The display unit 210 and the back light assembly220 are fixed and supported by a mold frame 400.

FIG. 7 is an exploded perspective view for showing the light guide plate224 and the mold frame 400 of the LCD device 100 according to the firstpreferred embodiment of the present invention shown in FIG. 6. FIG. 8 isa side view for showing the structure of the sidewall of the light guideplate shown in FIG. 7. FIG. 9 is a partially cut perspective view forshowing the structure of the light guide plate shown in FIG. 8. FIG. 10is a plan view for showing the light guide plate according to the firstpreferred embodiment of the present invention shown in FIG. 7.

Referring first to FIG. 7, the light guide plate 224 is a wedge typelight guide plate in which the thickness thereof becomes thinner furtheraway from a first end portion on which the light is inputted from thelamp 221 (see FIG. 6). However, the first preferred embodiment accordingto the present invention is applied in a case where the thickness of thefirst end portion of the light guide plate 224 is the same as a secondend portion opposite to the first end portion.

The first end portion of the light guide plate 224, i.e., both edgeportions of the first end portion that is received in a receiving spaceof the mold frame 400 towards a position at which the lamp 221 isinstalled, is cut off to form a third catching jaw 224 a ₁ and a fourthcatching jaw 224 b ₁. A first projection 224 a ₁′ and a secondprojection 224 b ₁′ extend outwardly from sidewalls of the third andfourth catching jaws 224 a ₁ and 224 b ₁ which respectively have athinner thickness than the third and fourth catching jaws 224 a, and 224b ₁.

Referring to FIGS. 8 and 9, the thickness t₁ of the second projection224 b ₁′ is thinner than the thickness t₂ of the fourth catching jaw 224b ₁. Meanwhile, the first projection 224 a ₁′ has the same thickness asthe second projection 224 b ₁′ and the third catching jaw 224 a ₁ hasthe same thickness as the fourth catching jaw 224 b ₁. If the first andsecond projections 224 a ₁′ and 224 b ₁′ bear up the weight of the lightguide plate 224, the thickness t₁ of the first and second projections224 a ₁′ and 224 b ₁′ may be thinner than the thickness t₂ of the thirdand fourth catching jaws 224 a ₁ and 224 b ₁. This will be describedbelow.

On the other hand, referring to FIG. 7, the lamp 221 and the lamp cover222 are received on one side of the receiving space of the mold frame400 that receives the light guide plate 224. Third and fourth catchingbosses 402 a and 404 a, which are engaged with the third and fourthcatching jaws 224 a ₁, and 224 b ₁ to prevent the movement of thehorizontal direction of the light guide plate 224, are integrally formedwith the mold frame 400 in both corner portions of the side wall onwhich the lamp 221 (see FIG. 6) is positioned.

Third and fourth catching covers 406 a and 408 a, for preventing thelight guide plate 224 received in the mold frame 400 from being deviatedto the vertical direction of the receiving space, are integrally formedwith the mold frame 400 in both corner portions of the side wallopposite to the third and fourth catching bosses 402 a and 404 a.

As shown in FIG. 10, when the light guide plate 224 is received in thereceiving space of the mold frame 400, the third catching jaw 224 a ₁ isengaged with the third catching boss 402 a and the fourth catching jaw224 b ₁ is engaged with the fourth catching boss 404 a. A portion of theboth corner portions of the second end portion of the light guide plate224 is inserted into the lower side of the third and fourth catchingcovers 406 a and 408 a.

FIG. 11 is a partially enlarged view of section “P1” for showing thefixing structure of the light guide plate 224 and the mold frame 400according to the first embodiment of the present invention shown in FIG.10.

Referring to FIG. 11, the gap between the side surface of the thirdcatching jaw 224 a ₁ and the sidewall of the mold frame 400 is narrowerthan the gap between the side surface of the second end portion of thelight guide plate 224 and the mold frame 400. This is because the firstprojection 224 a ₁′ is integrally formed with the light guide plate 224on the side wall of the third catching jaw 224 a ₁. The first projection224 a ₁′ has a slope shape in which the width thereof is narrower as itproceeds towards the second end portion.

Namely, the width of the third catching jaw 224 a ₁ of the light guideplate 224 is narrower as it proceeds towards the first end portion tothe second end portion. The width of the catching jaw 224 b ₁ (not shownin FIG. 11) also is narrower similar to the third catching jaw 224 a ₁.Therefore, the catching amount between the third and fourth catchingjaws 224 a ₁ and 224 b ₁ and the third and fourth catching bosses 402 aand 404 a is increased by the width of the catching body.

To describe this in more detail, as shown in FIG. 12, the widths W₃ andW4 of the third and fourth catching jaws 224 a ₁ and 224 b ₁ of thelight guide plate 224 are identical to each other before the first andsecond projections 224 a ₁′ and 224 b ₁′ are attached to the third andfourth catching jaws 224 a ₁and 224 b ₁. In this case, the widths of thefirst end portion and the second end portion of the light guide plate224 are the same. However, if the first and second projections 224 a ₁′and 224 b ₁′ are respectively attached to the respective sidewall of thethird and fourth catching jaws 224 a ₁ and 224 b ₁ the width W₁′ of thefirst end portion of the light guide plate 224 increases to the extentof the widths W₅ and W₆ of the first and second projections 224 a ₁′ and224 b ₁′ in relation to the width W₂ of the second end portion of thelight guide plate 224.

Therefore, as shown in FIG. 11, the catching force between the third andfourth catching jaws 224 a ₁ and 224 b ₁ and the third and fourthcatching bosses 402 a and 404 a is sufficiently obtained so as toprevent the light guide plate 224 from being shifted toward the lamp 221due to the exterior impacts. Further, since the first and secondprojections 224 a ₁′ and 224 b ₁′ have a slope shape in which the widththereof is narrower as it proceeds towards the second end portion, theconcentration of the light irradiated from the lamp 221 is prevented.Since the gap between the light guide plate 224 and the side wall of themold frame 400, except for the portion in which the first and secondprojections 224 a ₁′ and 224 b ₁′ are attached is sufficientlymaintained, the folding of the light guide plate 224 due to thetemperature and the humidity is prevented.

On the other hand, as shown in FIG. 11, both sidewalls of the mold frame400, i.e., the sidewalls corresponding to the first and secondprojections 224 a ₁′ and 224 b ₁′, respectively, have first and secondrecesses 410 a and 412 a in which the first and second projections 224 a₁′ and 224 b ₁′ are respectively received.

FIGS. 13 and 14 are views for showing the state in which the firstprojection 224 a ₁′ is received in the first recess 410 a shown in FIG.11.

Referring to FIG. 13, the width t₃ of the first recess 410 a is largerthan the thickness t₁ of the first projection 224 a ₁′ but it is smallerthan the thickness t₂ of the catching jaw 224 a ₁. Namely, the firstrecess 410 a has a depth enough to receive the first projection 224 a ₁′and the depth at which the first projection 224 a ₁′ is received in thefirst recess 410 a is adjusted by the third catching jaw 224 a ₁ asshown in FIG. 14. As not shown in the drawings, the second recessreceiving the second projection 224 b ₁′ has the same shape as the firstrecess 410 a.

As shown in FIG. 10, the catching force between the third and fourthcatching jaws 224 a ₁ and 224 b ₁ and the third and fourth catchingbosses 402 a and 404 a are sufficiently obtained so as to prevent thelight guide plate 224 from moving toward the lamp 221 in the mold frame400 due to the exterior impact.

If the exterior impact is applied not to the lamp 221 of the mold frame400, but is applied to both sidewalls of the mold frame 400 in which thefirst and second projections 224 a ₁′ and 224 b ₁′ are received, thefirst and second projections 224 a ₁′ and 224 b ₁′ of the light guideplate 224 firstly make contact with the respective sidewalls of the moldframe 400.

At that time, as the first and second recesses 410 a and 412 a receivethe first and second projections 224 a ₁′ and 224 b ₁′ until makingcontact with the third and fourth catching jaws 224 a ₁, and 224 b ₁ thefirst and second projections 224 a ₁′ and 224 b ₁′ are prevented fromcolliding with the mold frame 400 to thereby prevent a damage fromoccurring.

Particularly, when the openings of the first and second recesses 410 aand 412 a face to the third and fourth catching jaws 224 a ₁ and 224 b₁, and the sidewalls of the light guide plate 224 make contact with thesidewalls of the mold frame 400, the movements of the first and secondprojections 224 a ₁′ and 224 b ₁′ are stopped. In other word, thesidewalls of the light guide plate 224 make complete contact with thesidewalls of the mold frame 400, so that the movement of the light guideplate 224 is stopped.

Referring to FIGS. 15 and 16, the light guide plate 224 may be combinedto the mold frame 400 so that the first and second projections 224 a ₁′and 224 b ₁′ are respectively received at a desired depth in the firstand second recesses 410 a and 412 a.

On the other hand, when the first and second catching projections 224 a₁′ and 224 b ₁′ are inserted into the first and second recesses 410 aand 412 a, respectively, it is possible to prevent the light guide plate224 from moving away from the mold frame 400 toward the optical sheet226 similarly to prevent the horizontal movement of the light guideplate 224. Preventing the light guide plate 224 from moving away fromthe mold frame 400 toward the optical sheet 226 is carried out by meansof the third and fourth catching covers 406 a and 408 a.

As shown in FIG. 16, the thickness of an area in which the firstcatching jaw 224 a is overlapped with the third catching boss 402 a,when viewing from the lamp 221, is smaller than the thickness of thelight guide plate 224. Preferably, the thickness of the area in whichthe first catching jaw is overlapped with the third catching boss 402 isthe same as the thickness of the first projection 224 a ₁′.

Embodiment 2

Hereinafter, a LCD device according to the second embodiment of thepresent invention will be explained with reference to FIGS. 17 to 21.

FIG. 17 is an exploded perspective view for showing the LCD deviceaccording to the second embodiment of the present invention.

Referring to FIG. 17, the LCD device according to the second embodimentof the present invention has the same structure as the LCD deviceaccording to the first embodiment of the present invention shown in FIG.6, except for a back light assembly 220 and a back cover 400 a. Namely,the LCD device according to the second embodiment of the presentinvention shown in FIG. 17 is a monitor device that employs two lamps.In the second embodiment of the present invention, the same elementshaving the same function as those of the LCD device shown in FIG. 6 aredenoted by the same reference numerals. As shown in FIG. 17, thebacklight assembly 220 for providing the uniform light to the displayunit 210 is provided under the display unit 210. The backlight assembly220 has first and second lamps 221 a and 221 b, which are provided onboth sides of the LCD module 220 to generate the light, and the firstand second lamps 221 a and 221 b are protected by the first and secondlamp covers 222 a and 222 b. The light guide plate 224 has a sizecorresponding to the LCD panel 212 of the display unit 210 and guidesthe light generated from the first and second lamps 221 a and 221 btowards the display unit 210 while changing the path of the light. Thelight guide plate 224 may be a plurality of light guide plates, or asingle light guide plate.

The display unit 210 and the backlight assembly 220 are supported bymeans of the mold frame 400 as a receptacle assembly. A back cover 400 amade of a metal for isolating and reducing EMI generated from themonitor device is combined with the rear surface of the mold frame 400.

FIG. 18 shows the state in which the light guide plate according to thesecond embodiment of the present invention shown in FIG. 17 is receivedin the mold frame. FIG. 19 is a plan view for showing the structure ofthe light guide plate according to the second embodiment of the presentinvention shown in FIG. 10.

Referring first to FIG. 18, the first end portion of the light guideplate 224, i.e., both corner portions of the first end portion, which isfaced to the sidewall at which the first lamp 221 a is installed in thereceiving space of the mold frame, is cut off to form a fifth catchingjaw 224 a ₂ and a sixth catching jaw 224 b ₂. Further, the second endopposite to the first end portion of the light guide plate 224, i.e.,both corner portions of the second end portion, which is faced to thesidewall at which the second lamp 221 b is installed in the receivingspace of the mold frame 400, is cut off to form a seventh catching jaw224 c and an eighth catching jaw 224 d.

As shown in FIG. 19, the total width W1′ of the first end portion, atwhich the fifth and sixth catching jaws 224 a ₂ and 224 b ₂ are formed,is identical with the width W₂′ of the second end portion at which theseventh and eighth catching jaws 224 c and 224 d are formed. Third,fourth, fifth and sixth projections 224 a ₂′, 224 b ₂′, 224 c′ and 224d′ are respectively formed on the side surfaces of the fifth, sixth,seventh and eighth catching jaws 224 a ₂, 224 b ₂, 224 c and 224 d. Theoverall widths of the first and second end portions are wider than thewidth W₇ of the center portion of the light guide plate 224. The third,fourth, fifth and sixth projections 224 a ₂′, 224 b ₂′, 224 c′ and 224d′ respectively have a thickness smaller than that of the fifth, sixth,seventh and eighth catching jaws 224 a ₂, 224 b ₂, 224 c and 224 d. Thiswill be explained in detail with reference to FIGS. 19 and 20.

On the other hand, in the receiving space of the mold frame 400, whichreceives the light guide plate 224, the first lamp 221 a and the firstlamp cover 222 a are received at the side that faces the first endportion of the light guide plate 224, and the second lamp 221 b and thesecond lamp cover 222 b are received at the side that faces the secondend portion. Fifth and sixth catching bosses 402 b and 404 b, which areengaged with the fifth and six catching jaws 224 a ₂ and 224 b ₂ toprevent the movement of the light guide plate 224 toward the first lamp221 a, are integrally formed in the mold frame 400 at both cornerportions of the sidewall at which the first lamp 221 a is positioned.Seventh and eighth catching bosses 406 b and 408 b, which are engagedwith the seventh and eighth catching jaws 224 c and 224 d to prevent themovement of the light guide plate 224 toward the second lamp 221 b, areintegrally formed in the mold frame 400 at both corner portions of thesidewall at which the second lamp 221 b is positioned.

As shown in FIG. 20, when the light guide plate 224 is received in thereceiving space of the mold frame 400, the fifth catching jaw 224 a ₂and the fifth catching boss 402 b, the sixth catching jaw 224 b ₂ andthe sixth catching boss 404 b, the seventh catching jaw 224 c and theseventh catching boss 406 b, and the eighth catching jaw 224 d and theeighth catching boss 408 b are respectively engaged with each other toprevent the movement of the horizontal direction of the light guideplate 224.

Referring to FIG. 20, the gap between the fifth catching jaw 224 a ₂ andthe mold frame 400 is narrower than the gap between the center portionof the light guide plate 224 and the mold frame 400. This is because thethird projection 224 a ₂′ is integrally attached to the sidewall of thefifth catching jaw 224 a ₂. The third projection 224 a ₂′ has a slopedshape in which the width W₅ thereof is narrower as it proceeds towardsthe center portion of the light guide plate 224. The projections, havingthe same shape as the third projection 224 a ₂′, are respectively formedon respective sidewalls the sixth, seventh and eighth catching jaws 224b ₂, 224 c and 224 d on the light guide plate 224. The catching forcebetween the fifth, sixth, seventh and eighth catching jaws 224 a ₂, 224b ₂, 224 c and 224 d and the fifth, sixth, seventh and eighth catchingbosses 402 b, 404 b, 406 b and 408 b respectively increase to the extentof the widths W₅, W₆, W₅′ and W₆′ of the third, fourth, fifth and sixthprojections 224 a ₂′, 224 b ₂′, 224 c′ and 224 d′.

As shown in FIG. 19, the widths W₃, W₄, W₃′ and W₄′ of the fifth, sixth,seventh and eighth catching jaws 224 a ₂, 224 b ₂, 224 c and 224 d arethe same before the third, fourth, fifth and sixth projections 224 a ₂′,224 b ₂′, 224 c′ and 224 d′ are attached to the fifth, sixth, seventhand eights catching jaws 224 a ₂, 224 b ₂, 224 c and 224 d However, ifthe third, fourth, fifth and sixth projections 224 a ₂′, 224 b ₂′, 224c′ and 224 d′ are respectively attached to the respective sidewalls ofthe fifth, sixth, seventh and eighth catching jaws 224 a ₂, 224 b ₂, 224c and 224 d, the width W1′ of the first end portion and the width W2 ofthe second end portion of the light guide plate 224 are wider than thewidth W7 of the center portion of the light guide plate 224 by thewidths W5 and W6 of the third and fourth projections 224 a ₂′ and 224 b₂′. Therefore, as shown in FIG. 19, the catching forces between thefifth, sixth, seventh and eighth catching jaws 224 a ₂, 224 b ₂, 224 cand 224 d and the fifth, sixth, seventh and eighth catching bosses 402b, 404 b, 406 b and 408 b are sufficiently obtained. Thus, the lightguide plate 224 is prevented from moving toward the first lamp 221 a orthe second lamp 221 b due to the exterior impact. Further, since thethird, fourth, fifth and sixth projections 224 a ₂′, 224 b ₂′, 224 c′and 224 d′ respectively have a sloped shape in which the widths W₅, W₆,W₅′ and W₆′ thereof are narrower as it proceeds towards the centerportion of the light guide plate 224, the concentration of the lightirradiated from the first and second lamps 221 a and 221 b is prevented.

FIG. 20 is a sectional view for the first end portion of the light guideplate 224 shown in FIG. 19.

As shown in FIG. 20, the thickness t₁ of the third and fourthprojections 224 a ₂′ and 224 b ₂′ is thinner than the thickness t₂ ofthe fifth and sixth catching jaws 224 a ₂ and 224 b ₂. Furthermore, thefifth and sixth projections 224 c′ and 224 d′ respectively have athinner thickness than that of the seventh and eighth catching jaws 224c and 224 d. The third, fourth, fifth and sixth projections 224 a ₂′,224 b _(2′, 224) c′ and 224 d′ have the same width t₁.

FIG. 21 is a view for showing the structure of the mold frame shown inFIG. 18.

Referring to FIG. 21, the third, fourth, fifth and sixth recesses 410 band 412 b, 414 and 416 are respectively formed on both sidewalls of themold frame 400, i.e., the sidewalls corresponding to the third, fourth,fifth and sixth projections 224 a ₂′, 224 b ₂′, 224 c′ and 224 d′, toreceive the third, fourth, fifth and sixth projections 224 a ₂′, 224 b₂′, 224 c′ and 224 d′.

In the same manner as in the first embodiment of the present invention,the height of the openings of the third, fourth, fifth and sixthrecesses 410 b, 412 b, 414 and 416 are larger than the thickness t₁ ofthird, fourth, fifth and sixth projections 224 a ₂′, 224 b _(2′, 224) c′and 224 d′ but smaller than the thickness t₂ of the fifth, sixth,seventh and eighth catching jaw 224 a ₂, 224 b ₂, 224 c and 224 d.

Namely, the third, fourth, fifth and sixth recesses 410 b, 412 b, 414and 416 respectively have a depth enough to receive the third, fourth,fifth and sixth projections 224 a ₂′, 224 b ₂′, 224 c′ and 224 d′. Thedepth at which the third, fourth, fifth and sixth projections 224 a ₂′,224 b ₂′, 224 c′ and 224 d′ are respectively received in the fifth,sixth, seventh and eighth recesses 410 b, 412 b, 414 and 416 is adjustedby the fifth, sixth, seventh and eighth catching jaw 224 a ₂, 224 b ₂,224 c and 224 d.

As shown in FIG. 21, since the catching amount between the fifth, sixth,seventh and eighth catching jaws 224 a ₂, 224 b ₂, 224 c and 224 d andthe fifth, sixth, seventh and eighth catching bosses 402 b, 404 b, 406 band 408 b are sufficiently obtained, it is possible to prevent the lightguide plate 224 from moving toward the lamp 221 in the mold frame 400due to the exterior impact.

If the exterior impact is forced to both sidewalls of the mold frame400, i.e., the third, fourth, fifth and sixth projections 224 a ₂′, 224b ₂′, 224 c′ and 224 d′ in the state that the light guide plate 224 isreceived in the mold frame 400, the third, fourth, fifth and sixthprojections 224 a ₂′, 224 b ₂′, 224 c′ and 224 d′ of the light guideplate 224 firstly make contact with the respective sidewall of the moldframe 400.

At that time, as the third, fourth, fifth and sixth recesses 410 b, 412b, 414 and 416 receive the third, fourth, fifth and sixth projections224 a ₂′, 224 b ₂′, 224 c′ and 224 d′ until making contact with thethird, fourth, fifth and sixth catching jaws 224 a ₁, 224 b ₁, 224 a ₂and 224 b ₂, the third, fourth, fifth and sixth projections 224 a ₂′,′224 b _(2′, 224) c′ and 224 d′ are prevented from colliding with themold frame 400 to thereby prevent a damage.

Meanwhile, the light guide plate 224 may be combined to the mold frame400 in order for the third, fourth, fifth and sixth projections 224 a₂′, 224 b ₂′, 224 c′ and 224 d′ to be respectively received at a desireddepth in the third, fourth, fifth and sixth recesses 410 b, 412 b, 414and 416. Accordingly, the departure of the light guide plate 224 fromthe mold frame 400 toward the optical sheet 226 is prevented.Furthermore, when viewing from the first or second lamps 221 a and 221b, respective areas of which the fifth, sixth, seventh and eighthcatching jaws 224 a ₂, 224 b ₂, 224 c and 224 d are respectivelyoverlapped with the fifth, sixth, seventh and eighth catching bosses 402b, 404 b, 406 b and 408 b have a smaller thickness than the thickness ofthe light guide plate 224. Preferably, the thickness of each area inwhich the fifth, sixth, seventh and eighth catching jaws 224 a ₂, 224 b₂, 224 c and 224 d are respectively overlapped with the third, fourth,fifth and sixth catching bosses 402 b, 404 b, 406 b and 408 b is thesame as the thickness of the third, fourth, fifth and sixth projections224 a ₂′, 224 b ₂′, 224 c′ and 224 d′.

According to the LCD module and the LCD device, the catching jaws areformed at both corners of the end portion of the light guide plateopposite to the lamp received in the mold frame and the projectionswhich have the sloped shape extend outwardly from the respectivesidewalls of the catching jaws. Furthermore, the recesses arerespectively formed at the positions corresponding to the respectiveprojections in the sidewalls of the mold frame to receive theprojections, of which widths are respectively larger than the thicknessof the projections but smaller than the thickness of the catching jaws.

Accordingly, since the catching force between the catching bosses of themold frame and the catching jaws of the light guide plate increasesgreatly, the catching bosses of the mold frame are respectively andrigidly engaged with the catching jaws to prevent the light guide platefrom moving toward the lamp even if an exterior impact is forced to theLCD device. In addition, even though the exterior impact is applied tosidewalls of the mold frame, the projections and the catching jaws canbe prevented from being damaged because the projections are respectivelyreceived in the recesses of the mold frame. Further, since theprojections are formed in a sloped shape, the concentration of the lightinputted from the lamp is prevented.

Although the preferred embodiments of the present invention have beendescribed, it is understood that the present invention should not belimited to these preferred embodiments but various changes andmodifications can be made by one skilled in the art within the spiritand scope of the present invention as hereinafter claimed.

1. A liquid crystal display module, comprising: a lamp unit; a lightguide plate having a projection formed on an outer edge portion of asidewall thereof, and having first, second, third, and fourth sides; anda mold frame for receiving the lamp unit, the mold frame includingfirst, second, third, and fourth sidewalls that are connected with eachother and respectively correspond to the first, second, third, andfourth sides of the light guide plate to form a substantiallyrectangular frame to define a receiving space for receiving the lightguide plate therebetween, and further having a recess formed on an inneredge portion of one of the first, second, third, and fourth sidewalls ofthe mold frame corresponding to the projection wherein the projection isinserted into the recess.
 2. The liquid crystal display module of claim1, wherein the projection is formed in a sloped shape having a widththat gradually decreases from a first end portion to a center portion ofthe light guide plate.
 3. A display module, comprising: a mold frameincluding a plurality of sidewalls having first, second, third, andfourth sidewalls, the first, second, third, and fourth sidewalls beingconnected to each other to form a substantially rectangular frame todefine a receiving space, the mold frame having a catching bossprotruding from a first portion of an inner surface of a first sidewallof the plurality of sidewalls and a first recess recessed from a secondportion of the inner surface of the first sidewall, wherein the firstportion corresponds to a corner portion and the second portion adjoinsthe first portion; a lamp unit arranged in the mold frame; and a lightguide plate having first, second, third, and fourth sides, receivedbetween the plurality of sidewalls defining the receiving space of themold frame and having a catching jaw arranged corresponding to thecatching boss and a first projection inserted into the first recess,wherein the first recess has a width that is larger than a thickness ofthe projection but smaller than a thickness of the catching jaw, whereinthe first, second, third, and fourth sidewalls of the mold framerespectively correspond to the first, second, third, and fourth sides ofthe light guide plate.
 4. The display module of claim 3, wherein themold frame further comprises a catching cover covering a corner portionof the light guide plate so as to prevent vertical deviation of thelight guide plate.
 5. The display module of claim 3, wherein the lightguide plate is a wedge type light guide.
 6. The display module of claim3, further comprises a second recess formed on a second inner sidesurface of a second sidewall of the plurality of sidewalls, the secondinner side surface facing the first inner side surface; and the lightguide plate further comprises a second projection inserted into thesecond recess.
 7. The display module of claim 6, wherein the firstprojection is formed adjacent to the catching jaw.
 8. The display moduleof claim 3, further comprising a second lamp unit arranged in the moldframe.
 9. A display device, comprising: a light guide plate havingfirst, second, third, and fourth sides, and having a catching jaw at acorner thereof and a projection formed on a side surface thereof; and amold frame including a plurality of sidewalls having first, second,third, and fourth sidewalls, the first, second, third, and fourthsidewalls being connected to each other and respectively correspond tothe first, second, third, and fourth sides of the light guide plate toform a substantially rectangular frame to define a receiving space forreceiving the light guide plate therebetween, and having a catching bossformed corresponding to the catching jaw and a recess formedcorresponding to the projection on an inner surface of a first sidewallof the plurality of sidewalls defining the receiving space, wherein theprojection is inserted into the recess, and the recess is spaced apartfrom at least one of an upper surface and a lower surface of the moldframe, wherein the recess has a width that is larger than a thickness ofthe projection but smaller than a thickness of the catching jaw.
 10. Thedisplay device of claim 9, wherein the catching boss protrudes from afirst portion of the inner surface of the first sidewall and the recessis recessed from a second portion of the inner surface of the firstsidewall, wherein the first portion corresponds to a corner portion ofthe first sidewall and the second portion adjoins the first portion. 11.The display device of claim 9, wherein the mold frame further comprisesa catching cover covers a corner portion of the light guide plate so asto prevent vertical deviation of the light guide plate.